Menopause and lead body burden among US women aged 45-55, NHANES 1999-2010.

Background: Environmental factors in menopause have received limited attention. Lead is a known reproductive toxicant associated with delayed puberty in girls that may also affect menopause.

Methods: The odds of menopause among US women aged 45-55 were estimated in the National Health and Nutrition Examination Survey, 1999-2010, in relation to quartiles of blood lead. Women still menstruating (n=2158) were compared to women with natural menopause (n=1063). Logistic regression models included age, race/ethnicity, current hormone use, poverty, smoking and where available, bone density or bone alkaline phosphatase.

Results: Lead levels (ug/dL) were higher in menopausal women, geometric mean (standard error)=1.71 (0.04) vs. 1.23 (0.02). Adjusted odds of menopause and 95% confidence intervals for lead quartiles (lowest quartile referent) were 1.7 (1.0-2.8), 2.1 (1.2-3.6), and 4.2 (2.5-7.0) respectively. Results adjusting for bone markers were generally similar but had less precision.

Conclusions: Blood lead was associated with natural menopause in US women even after adjustment for bone turnover. This raises concern that lead exposure, even at low levels, may shorten women's reproductive lifespan.